Stabilization of sulphur-containing compounds and systems



BEST AVAILABLE COPY Patented Sept. 13, 1938 UNITED STATES STABILIZATION OF SULPm-CON'IAINING COMPOUNDS AND SYSTEMS Morris 8. Kharasch, Chicago, 111., assignor to Eli Lilly and Company, Indianapolis, 11111., a corporation of Indiana No Drawing.

Application May 14, 1934,

Serial N0. 725.482

11 Claims.

It is the object of my invention to stabilize against oxidation by oxygen those compounds in which such oxidation is catalyzed by the presence oi ions oi copper, manganese, and iron; and

especially compounds of that type which contain sulphur.

Many compounds containing sulphur are restricted in their usefulness by their tendency to be oxidized by oxygen, and the consequent i'or- 0 mation of undesirable products; and to have that oxidation catalyzed tremendously by the presence of the metal ions mentionedcopper, manganese. and iron. It is to a stabilization and improvement of those compounds that my present invention is generically directed.

I have discovered that this catalysis may be largely if not wholly inhibited by the presence of an aliphatic dlamine, preferably an aliphatic 1,2- diamine; and that such inhibition may be obtained by having the aliphatic dlamine present either as a separate added ingredient or as part of the compound being stabilized or 01' a copresent compound. That is, the aliphatic dlamines may be either added ingredients initially separate from the compound to be stabilized, and either dlamines per se or parts oi compounds which contain such dlamines, or may be initially part of the compound to be stabilized. Therefore. when in my claims I state that a dlamine is present in the solution, I intend to include all of these situations; because they are in eflect generically the same.

Various aliphatic dlamines may be used i'or the stabilization contemplated by my invention, including the following:

a. 1.2-ethylenediamine,

b. 1,2-propyienedlamine.

c. N-phenylethylenediamine,

H I Oglzh-N-OHg-CHr-NH.

d. 1,2-butylenediamine,

e. 1,3-propylenediamine,

I. Condensation products of the dlamines with aldehydes, and

Salts oi the dlamines, especially with weak acids.

Of these various dlamines, I prefer the 1,2- diamines, especially 1,2-ethyienediamine and 1,2- propylenediamine.

The aliphatic dlamine probably exerts its inhibiting action by forming extremely stable complexes with the metallic ions, of copper, manganese. and iron, and by thus preventing such ions from exerting their catalytic efl'ect.

My invention is oi broad scope. for sulphurcontaining compounds 0! many different types are sensitive to catalysis by these metal ions, and I intend to include in the present invention all such compounds containing sulphur.

As illustrations 01 this broad scope of my invention. I give below a number oi examples, which are merely illustrative and are not given as limitations oi that broad scope. These illustrative examples show that the stabilization by such an aliphatic dlamine is accomplished in both organic and inorganic compounds which are sensitive to this catalysis; and tail into several general classes and sub-classes, as follows:

1. Inorganic compounds-tetravalent-sulphur salts, by which I include sulphites and hyposulphites, which although included under the generic claims of the present application are claimed specifically in my co-pending application Serial No. 725,483, filed May 14, 1934.

A. Sulphites:

1. Sodium sulphite,

2. Potassium sulphite,

3. Ammonium sulphite.

4. Other sulphites in which the metal ions of copper, manganese, and iron tend to catalyze oxidation by oxygen,

5. Inherently stable sulphites. in which the aliphatic 1,2-diamine is the base portion of the sulphite.

. Hyposuiphites (hydrosulphites):

1. Sodium hyposulphite (NaaBzOa commonly known in the trade as sodium hydrosulphite),

2. Potassium hyposulphite,

3. Other hyposulphites in which said metal ions tend to catalyze oxidation by y 4. Inherently stable hyposulphites, in which the 1,2-aliphatic dlamine is the base portion of the hyposulphite.

II. Organic thlol compounds:

A. Compounds of the following general formula:

(2) R-S-Rs in which R is either hydrogen, or a metal oi the class consisting of mercury, arsenic, antimony,. and bismuth, or an organo-metailic group stable toward water and including a metal of such class joined by one valence bond to the sulphur atom; and Rn is an organic-acid group having a carbon atom bonded directly to the sulphur atom and including either hydrogen to iorm the acid or an alkali metal or an alkaline-earth metal or ammonium or a substituted ammonium to term the corresponding salt or NH: to form the corresponding amide. Examples oi this sub-class are:

1. Compounds represented by the follow ing formula:

(3) HBRss in which RAe has the same significance as before.

2. Compounds represented by the following formula:

(4) Me-S-Rm:

in which RAo has the same significanoe as before, and Me indicates a metal of the class consisting oi mercury, arsenic, antimony, and bismuth joined by one or more valence bonds to the radical S-RM and havin any remaining valence bonds satisfied in any desired manner.

These organic compounds may be subdivided into the following classes:

a. Certain alley] and alicyclic mercuric sulphur compounds in which the R of Formula 2 above is bivalent mercury joined by one valence bond to. the sulphur atom and by the other to an alkyl or alicyclio radical, of the general type shown in BEST AVAILABLE COPY or bismuth, having one or more oi its valence bonds attached to the B-RA group of Formula 2.

I will discuss some 0! these examples separately.

Class I, sub-class A 1. Sodium sulphite has many uses, both in itself and as a stabilizer of unstable systems, but of itself is quite unstable toward oxidation by oxygen of the air. especially in the presence of the metal ions 0! copper, manganese, and iron. The measure of its deterioration by oxidation can be followed by its loss in iodine titre. The stabilization of sodium-sulphite solutions against metal catalysis by added 1,2-ethylenediamine is shown in the following Tables I and II:

Tasu: I

Stabilization of sodium sulphite solutions by the addition 0] LZ-ethyienediamine Concentration of sodium sulphite-lzlOOO.

Concentration of added copper ions, when copper is addedl:200,000.

Iodine titre given in cc. of 0.015N iodine solumy Patent No. 1,672,615, granted June 5, 1928. tion per 5 cc. of sodium-sulphite solution. The The stabilization 01 these compounds, although accuracy of the iodine titrations is 0.2 cc.

Iodine titre Eth l odi ino ddod Solution Y an m a 01'! Later-after ra" n time indicated days Sodium Iulphito. 4. 54 2.9l (2 hrs.). None 0.00 (3 days).

Sodium sulphito i-ooppor 001- 4. 45 0.30 (B hm).

photo.

Hedging! sulphito+Na0H to give 3. 74 1.68 (2 hrs.) N p 0.00 2 a Ill- 0 Sodium snlphite+Na0H to give 8. 28 0.00 (2 days).

pH 0+ooppor sulphate.

Sodium snlphito NH40H (0 4.33 3.86 (4 hrs.). N drops per 00000. 2.27 (22 hrs.).

one.

Sodium suIphitH-NHmH (0 2.7! 1.71 541111.).

drops per 600 oo.)+oopper 0.00 221111.). sulphate.

' Sodium lulphlto. 4. 60 4.37 (8 days). 3. 89 Ethyienodlamina to give pH ii.

Sodium lulphita-i-oopper lul- 4. 45 0.30 (3 days). 1.01

photo.

Bodlum lulphito. 4. 41 4.43 (3 days). 4. 4i Ethylsnsdiamino in 0100s: (it

drops per i500 00.). aulphito+oopper sub 4. 46 4.30 (8 days). 4. 10

included under the generic claims oi! the present Tan: II

application, is specifically claimed in my copending application Serial No. 111,822, filed February 17, 1934, now Patent No. 2,012,820, granted August 2'7, 1935.

0. Certain mercuric sulphur compounds in which the R of Formula 2 above is bivalent mercury having each of its valence bonds attached to a BRM group of Formula 2.

0. Certain arsenous, antimonous, and his- I muthous sulphur compounds in which the R of Formula 2 above its trivalent arsenic, antimony,

Relative 217001: of copper, manganese, and iron on rate of oxidation of sodium sulphite, alkaliniaed with sodium hydroxide and with. 1,2- ethulenediomtnc respectively Concentration of sodium sulphite-1:i000.

Concentration of sodium hydroxide, when used, is to give pH 9.

Concentration of ethylenediamine, when used, isnii 9drops per 500 00., which gives in excess 0! p 3 BEST AVAILABLE COPY Iodine titre is given in cc. of 0.0l5N-iodine solution per 5 cc. of sodium-sulphite solution. The accuracy of the iodine titrations is z 0.2 cc.

Class I, sub-close B 1. Sodium hyposulphite, like sodium suiphite, has various uses. both in itself and as a stabilizer Iodine um o Added metal ions Sodium sulphite solution 513" Aiter 20 hours None. With added NaOH. '2. 4a 0.10

With added ethylenediamine. 4. 09 4.00

With added NsOH. 4. s0 0. oc Cu" moopoo.

With added ethylenediamlne. 4. 45 4. 30

(After 07 hours) with added NaOH. 3. 41 L13 Mn 200,000.

With added ethylenediamine. 4. 31 3. 81

With added NaOH. 2.10 0.00 Fe"1:50.000.

With added ethylonedlamine. 4. 34 4.31

The stabilization oi sodium sulphite by added of unstable systems, but of itself is also quite 1,2-propylenediamine and by added N-phenylunstable toward oxidation by oxygen of the air. ethylenediamine, in contrast to that produced by especially in the presence oi the metal ions of ethanolamine (which also has some stabilizing effect), is shown in the following Table III:

TABLE III Stabilization of sodium sulphite solutions by the addition of ethanolamine, 1,2-propulenedtamine, and N-phenulethvlewedtamine copper. manganese, and iron. The measure of its deterioration by oxidation can also be followed by its loss in iodine titre.

The stabilization of sodium hyposulphite (Na/28:04) by ethylenedlamine in the presence of copper ions is shown by the following Table IV:

TABLI IV Efi'ect of copper on rate of oxidation of sodium Mmosulphite alkalinized with sodium hvdrozide and with ethylenediamlne respectively Concentration or sodium sulphite1:1000. Concentration oi added copper ions-12200000.

500 cc, Iodine titre given in cc. 0! 0.015N iodine solu- 4o Iodine titre Added stabilizer Solution 3 it if it hours hours hours Bosiium sulphite N sOH to give pH 4.66 0. 21 None. u

Sodium sulphlte NsOH to give pH 2. 23 1. l0

9 copper sulp etc. sodium lulpbite. 4.05 4.33 4.25 4.12 Etbsnolsmlne.

Sodium sulphite 4- copper sulphate. 4. 40 0. 05 l. 71 0. 00

Sodium sulphite. 4.50 4.5:! 4. s: 4.25 1,2-propylenedismlne.

Sodium mlpbite copper sulphate. 4. 48 4.50 4.80 4.10

sodium sulphite. 4.07 an am 1.73 N-phenylcthylene diemine.

Bodlnm eulphite copper sulphate. 4. 40 8. 16 1.90 0- Similar ei'iects are obtainable on other aultion per 0 cc. of sodium-sulphite solution. The phites, as of potassium. accuracy of the iodine titrations is 10.2 cc.

Iodine am After bubbling u: Solution through- Alter 7 in ll For 2 For 0 houn hours hours Sodium by uiphite-I-OuBQ-i-NaOH to give pH .0 4.08 8.80 0.10 0.10 Sodium hypo sulphlte+Cu8O +ethylenedismine to give pH 0.0 J! 407 4. 04 4. i0

TABLE V Stabilization of sodium sulphite solutions by condensation products of 1,2-diamines and! aldehydes Concentration of sodium sulphite-l:1000.

Concentration oi added copper ions--1:200,000.

Concentration of dlamine-aldehyde concentration products-M1000.

Iodine titre given in cc. of 0.015N iodine solution per 5 cc. of sodium-sulphite solution. The accuracy of the iodine titrations is 1-0.2 cc.

iodine titre Solution Orifi- After 20 in hours Sodium sulphite 4. 20 0.10

Sodium sulphlte+condcnsetlon product of ethylenedismine with occtaliichy c 5.10 4.75

Sodium suiphitc+condcnsatlon roduct of propylcnedlamine with salicylic n rlciiydc. 4.90 4. 34

Such condensation products of 1,2-dlarnines with aldehydes may be obtained in various ways. A convenient way is by treating an ether solution of the aldehyde with the desired dlamine, such as ethylenediamine. In some cases a solid separates out, as in the case of propylenediamine with salicylic aldehyde. This last-mentioned compound is a bright yellow solid, which melts at 118-123 C. Ethylenediamine and salicylic aldehyde also yield a bright yellow solid, which melts at about 125 C. Ethyienediamine and acetaldehyde yield a white solid, which melts at about 108 C.

In all of these stabilizations, the aliphatic diamine probably exerts its inhibiting or stabilizing action by forming extremely stable complexes with the metallic ions, as of copper, manganese, and iron, and by thus preventing such ions from exerting their catalytic effect.

Such condensation product may be used eifectively to stabilize other sulphites, as of potassium, etc; and also to stabilize various hyposulphites. as of sodium. potassium, etc.

Class I, sub-classes A and B, species 5 In the preceding Tables I to V inclusive, the stabilization has been initially of an existing sulphite or hyposulphite with a 1,2-diamine which was not part of the salt molecule. It is possible, however, to prepare a new and in- BEST AVAILABLE COPY iron, and even in a solution which is neutral or slightly alkaline-a property which is unique for tetravalent-sulphur salts.

These dlamine salts may be prepared in various ways. The dlamine sulphites may be prepared by causing the desired dlamine to react with sul phur dioxide or sulphurous acid; and the diamine hyposulphites by electrolytic reduction of the dlamine sulphites.

An example of these dlamine salts is ethylenediamine sulphite. It is perhaps most simply prepared by passing sulphur dlo'..ide into either an absolute or aqueous alcoholic solution of 1,2- ethylenediamine or into an acetone solution of such dlamine; upon which the salt separates in solid form.

Ethylenediamine sulphite melts at 1'l31'l5 C. with decomposition. It is white, and quite soluble in water. The water solution is about pH 6.7. The analysis of the salt for nitrogen and sulphur indicates that it contains one mole of ethylenediamine to one mole of sulphurous acid. It is quite stable against metal catalysts, and is very effective as a stabilizer of those easily oxidizabie benzenoid compounds which are unstable in the presence of ions of copper, manganese, or iron. It probably has the following formula:

BIN-C Hg-C Hr-NBJ F EN-CHPC Hr-NHl Another example is propylenediamine sulphite. It may be prepared analogously to ethylenediamine sulphite: and is similar thereto inmost respects. It melts at 162 C., with decomposition. It also is quite stable against metal catalysts, and effective as a stabilizer of these benzenoid compounds.

Ethylenediamine hyposulphiae may e obtained by reducing ethylenediamine sulphite.

These inherently stable sulphites or hyposulphltes act substantially like my stabilized sodium sulphite and hyposulphite, to stabilize unstable systems. Thus ethyienediamine sulphite is substantially as eflective as a stabilizer of these systerm as is my stabilized sodium sulphite.

Class II, sub-class A.

1. Among the organic thio compounds which may be stabilized by the aliphatic LZ-diamines, are thefollowing:

a. Cysteine, which has the following formula:

(6) HSCHzCIUNHDCOOH b. Thiosalicylio acid, which has the following formula:

coon

c. Thioglycollic acid, which has the following formula:

(8) HSCHsCOOH d. p-Thiobenzene sulphonic acid, which has the following formula:

ns-Osoia OOQH 1:. Sodium mercurithlosalicylate, having the following formula:

COONI c. Mercurithloglycollic acid, having the following formula:

(12) HE(SCH2COOH):

d. Sodium mercurithioglycollate, having the following formula:

(13) HMSCHzCOONM e. Mercuri-p-thiophenyl acetic acid, having the following formula:

s-O- mco on e-O-omooon 1. Sodium mercuri-p-thiophenyi acetate, having the following formula:

s-O-omcoom sOcmcoom a. Arsenous-thioglycollic acid, having the following formula:

(16) AB(SCH2COOH)1I h. Sodium arsenous-thioglycollate, having the following formula:

(1"!) A5 (BCHiCOONS) 3 i. Arsenous-thiosalicylic acid, having the following formula:

(13) As-B BEST AVAILABLE COPY 1. Sodium arsenous-thiosaiicylate, having the following formula:

1:. Sodium antimonous-thioglycollate, having the following formula:

BbBOHa OONI 1. Antimonous thloglycollamide, having the following formula:

(21) Bb(SCH2CONHz)a m. Sodium bismuthous-thioglycollate, having the following formula:

(22) Bi (SCI-IzCOONa) These may be stabilized against oxidation, as in the case of the other compounds, either by having the aliphatic diamine as part of the compound or by having it merely as an added ingredient. when the diamine is part of the compound, it reacts with the acid to form a diamine salt; but when the compound to be stabilized is already a salt, the diamine may be merely copresent in solution. 8,-Among the alkyl and alicyclic mercuric sulphur compounds in which the R. of Formula 2 or the Me of Formula 4 above is mercury joined by one valence bond to the sulphur atom and by the other to an, alkyl or alicycllc radical, included generically in this application but claimed specifically in my aforesaid co-pendlng application Serial No.

711,822, are the following:

. Ethylmercurlthiosalicylic acid;

. Sodium ethylmercurithiosalicylate:

. Cyclohexylmercuri-p-thiopropionic acid;

. Sodium cyclohexylmercuri p thiopropionate;

Methylmercurlthioglycollic acid:

Sodium methylmercurlthioglycollate;

. Methylmercuri p thiobenzenesulphonic acid;

71. Sodium methylmercuri-p-thiobenzenesulphonate;

i. Butylmercurithiosalicylic acid; and

1. Sodium butylmercurithiosalicylate.

In all the salts which have been mentioned, other alkali metals or an alkaline-earth metal or ammonium or a substituted ammonium may be used instead of sodium.

In addition, amides may be formed from certain of the acids, as illustrated for instance by ethyl mercuri-p-thiobenzene sulphonamide, which has the following formula:

mmmsO-somn,

In stabilizing compounds of this type, they are one cdissolved in solutions containing the desired aliphatic diamine, or the desired aliphatic dlamlne is added to a solution of the compound if the compound is soluble. In the case of the acids, the aliphatic diamine reacts with the acid to BEST AVAILABLE COPY form a salt; of which an example is ethylenediamine ethyl mercuri-thiosalicylate, the formula of which is probably either O lHr-HI- B No exact quantity of the aliphatic 1,2-diamine is necessary in any of these stabilizations; save of course that in forming diamine salts it is necessary to have enough of the diamine, and often desirable to have some excess beyond a molecular equivalent. I have been able to obtain eflective stabilizations with the amount of aliphatic diamine varying from as much as 50 moles thereof, to as little as one-half mole thereof in some instances. But the antimonous compounds, however, seem to require a little more of the diamine than do the other diamines for effective stabilization; and therefore I prefer to use an excess of the aliphatic 1,2-diamine, in terms of molecular equivalents in stabilizing antimonous compounds.

Instead of stabilizing by adding the diamines themselves, or condensation products thereof with aldehydes, I may also use known salts of the diamines, such for instance as the acetate, carbonate, or the tartrate. 'In general, if such salts are used, it is preferable that they be diamine salts of rather weak acids. With some of the compounds outlined above. it is essential to maintain the hydrogen ion concentration within a proper range, in order to get eflective stabilization. This range differs for the different compounds.

I claim as my invention:

1. The process of stabilizing against oxidation by oxygen a solution of a sulphur-containing compound in which otherwise such oxidation is catalyzed by the presence of ions of copper, manganese or iron; which consists in adding an allphatic 1,2-diamine to the solution.

2. The process of stabilizing against oxidation by oxygen a solution of a sulphur-containing compound in which otherwise such oxidation is catalyzed by the presence of ions of copper, manganese, or iron; which consists in adding ethylenediamine to the solution.

3. A solution of a sulphur-containing compound in which oxidation by oxygen tends to be catalyzed by the presence of ions of copper, manganese, and iron, which solution contains an all-- phatic 1,2-diamino to stabilize it against such oxidation.

4. A solution of a sulphur-containing compound in which oxidation by oxygen tends to be catalyzed by the presence of ions of copper, manganese, and iron, which solution contains an uncombined aliphatic 1,2-diamine to stabilize it against such oxidation.

5. A solution of a sulphur-containing compound in which oxidation by oxygen tends to be catalyzed by the presence of ions of copper, manganese, and iron, which solution contains ethylenedlamine to stabilize it against such oxidation.

6. A solution of a sulphur-containing compound in which oxidation by oxygen tends to be catalyzed by the presence of ions of copper, manganese, and iron, which solution contains uncombined ethylenediamine to stabilize it against such oxidation.

7. A solution of a sulphur-containing compound in which'oxidation by oxygen tends to be catalyzed by the presence 01 ions of copper, manganese, and iron, in which solution an aliphatic 1,2-diamine is present in the form of a salt.

8. A solution of a sulphur-containing compound in which oxidation byoxygen tends to be catalyzed by the presence of ions of copper, manganese, and iron, in which solution ethylenediamine is present in the form of a salt.

9. The process of stabilizing sodium arsenousthioglycollate against oxidation by oxygen, which consists in adding an aliphatic 1,2-diamine thereto.

10. The process of stabilizing antimonous thicglycollamide against oxidation by ozqrgen, which consists in adding an aliphatic 1,2-diamine thereto.

11. The process of stabilizing sodium bismuthous thioglycollate against oxidation by oxygen, which consists in adding an aliphatic 1,2-diamine thereto.

MORRIS S. KHARABCH.

BEST AVAILABLE COPY CERTIFICATE OF CORRECTION Patent No. 2,150,521. September 15, 1958.

MORRIS S. KHARASCH.

It is hereby certified that error appears in the printed spe'cification of the above numbered patent requiring correctionas follows: Page 2, first column, line 1, beginning with the numeral and,

words "1. Compounds represented" strike outall to and including the table ending in line 75, second column of page 5, and insert instead the following:

1. Compounds represented by the followin: formula:

( 3) H-S-Raa in which RM has the same signincance as before.

2. Compounds represented by the followin: formula:

(4) Me8-Ras in which Ru has the same signincance as before. and Me indicates a metal of the class consistin: oi mercury, arsenic, antimony. and bismuth joined by one or more valence bonds to the radical 4-H. and havlna an remaining valence bonds satisfied ii any desired manner.

These organic compounds may be subdivided into theiollowina classes:

a. Certain alkyl and alicyclic mercuric sulphur compounds in which the R of Formula 2 above is bivalent mercury joined by one valence bond to the sulphur atom and by the other to an alkyl or alicyclic radical. of the seneral type shown in my Patent No. 1,672,815, ranted June 5, 1928. The stabilisation 0! these compounds. although included under the generic claims of the present application, is specifically claimed in my eopending application Serial No. 711,822, died February 17, 1934. now Patent No. 2,012,820, granted Auaust 27, 1936.

0. Certain mercuricsulphur compounds in which the R of I'brmula'2 above is bivalent mercury havins eachof its valence bonds attached to a --SRM zroup of Formula 2.

0. Certain arsenous, antimonous, and blamuthous sulphur compounds in which the R of Formula 2 aboveis trivalent arsenic, antimony, or bismuth, having one or more of its valence bonds attached to the-k3 group oi Formula 2.

I will diseuss'some oi these examples separately.

C'lasa I. sub-class A 1. Sodium sulphite has many uses, both in itself and as a stabilizer of unstable systems, but of itself is quite unstable toward oxidation by oxygen of the air, especially in the presence of the metal ions ot'copper, manganese, and iron. The measure of its deterioration by oxidation can be followed by its loss in iod ne titre. The stabilization of sodium-sulphite solutions against metal catalysis by added iz-ethylenediamine is shown in the following Tables I and II:

TABLI I Stabilization of sodium sulphite solutions by the addition of LZ-ethrlenedtamine Concentration of sodium sulphite--1:1000. Concentration of added copper ions.

copper is added1:200,000.

Iodine titre given in cc. of 0.015N iodine solution per 5 cc. oi. sodium-sulphite solution.

accuracy of the iodine titrations is :02 cc.

when

The

Iodine um Eth lenodiamine added Solution 1m: aiter {{f' time indicated 'miim mipmu. '4. m hm). None 0.00 days).

Sodium snl pm mi Q 01 mm) sagg n u town-0H to in s. 14 us (a in). mm 0.00 (2 a sodiumsnlphiwl-Naoflto so us one a D HooDoIrn Phma Sodium suiphi Na on a u: as 4 m. NM dropupermoa.

Bodium sulphits+NH40H (a an 1.11 nm. (in m was. MW lodiumml mu. days). lthylenodiamlmtodnpnfl. p "a saga]: sulphiMcoppI suius no a am). 1.01 sodium ml m. I am In u phi an 4.4: (I am). 4.41 drops purmoai. 8%.: mIphiui-oom lnitit 0006!!!)- an BEST AVAILABLE co TABLIII BEST AVAILABLE CQPY 9 Concentration of sodium suiphite1:1000.

Concentration or sodium hydroxide, when used, is to give pH 9.

Concentration oi ethyienediamine. when used,

is; 9drops per 500 cc.. which gives in excess or p Iodine titre is given in cc. of 0.015N iodine solution per 5 cc. of sodium-suiphite solution. The accuracy of the iodine titrations is i 0.2 cc.

Iodine titro Added metal ions Sodium suiphiu solution AM so hours None. With lddbd NaOH. 5. 43 ,0. with sddod ethyienedismine. 4. 4.00

With added NsOH. 4. I 0. wmi added th 1 ediami us no 0 an no.

y (AM 61 hours) with added NlOH. I. 01 1.18 Mn" 1300.000.

With added ethyienediemine. L87 3. 01

with added NlOH. 3-

with addnd ethyienedismins. 4. M i. 81

The stabilization of sodium suiphite by added IB-propyienediamine and by added bl-phenylethyienediamine, in contrast to that produced by ethanolamine (which also has some stabilizinl eflect). is shown in the following Table III:

Tiisu III Stabilization of sodium sulphite solution by. the

addition of ethanotaminc, LZ-wopulenodiamine, and N-phenyiethylenediomine Iodinetitre 1 a as in hows hours More Bo dium lulphlh NlOH M HIDE 4.08 0.31

None

Sodium sniphite NIOH to VI H I. II 1. 10

e copper snip tote. p I

sodium sui bite. us- 4. Ethsnolunine. a "a .1,

Sodium sniphiu +ceppqmiphate. 4.46 8.86 1.71 0.00

' Sodium mi hi.

1,2-propyl0n0dhmine. p t a n n Sodium suiphite ooppl sulphate. I. G '4. 60 4. II 4.10

Sodium miphit'e. I. 01 a n a 10 an N -phenyiethyiene dlsmine.

Sodium suiphito +.copp 4. 40 I. 10 l. 90 0. B0

Similar eflects are obtainable on other sulphites, as of potassium.

Class I, sub-class B 1. Sodium hyposulphite, like sodium suiphite. has various uses. both in itseli' and as a stabilizer of unstable systems. but of itself is also quite unstable toward oxidation by oxygen of the air. especially in the presence of the metal ions of copper, manganese, and iron. The measure of its deterioration by oxidation can also be followed by its loss in iodine titre.

The stabilization of sodium hyposulpbite (NazSzOO by ethylenediamine in the presence ofcopper ions is shown by the following Table IV:

TAaLs IV Eflect of copper on rate of oxidation of Main huposulphite alkalinized with sodium hvdroz ide and with ethvlenediamine respectively Concentration of sodium sulpbite1:1ll00. Concentration of added copper ions-200,000. Iodine titre given in cc. of 0.015N iodine solution per 5 cc. of sodium-sulphite solution.'1'he accuracy or the iodine titrations is $0.2 cc.

BEST AVAILABLE COPY page L first column, lines 21; to 55inclusive, marginal lines in the table; and second column, lines 25, 56-57 and 72, for "catalysts" read catalysis; same page and column, line 28,

in the formula, for 3 (Seal) read insert vertical and that the said Letters Patent should be read with this correction therein that the -same may conform to the record of the case in the Patent Office. Signed and sealed this 21 th day of January, A. D. 1959.

Henry Van Arsdale Acting" Commissioner of Patents 

